1. Field
Apparatuses and methods consistent with exemplary embodiments relate to image sensors having improved light utilization efficiency and methods of manufacturing the same
2. Description of the Related Art
Color display apparatuses and color image sensors, respectively, display images of various colors and detect the color of incident light. Currently available color display apparatuses and color image sensors generally employ a red, green, and blue (RGB) color filter structure in which, for example, two green filters are arranged in two out of every four pixels and a blue filter and a red filter are arranged in the other two of every four pixels. Alternately, a cyan, yellow, green, and magenta (CYGM) color filter structure may be used in which each four pixels include one pixel each of cyan, yellow, green, and magenta color filters.
However, since a typical absorption-type color filter absorbs light of colors other than the corresponding filter color, the light utilization efficiency thereof is low. For example, in the case of an RGB color filter, the RGB color filter transmits only one-third of the light incident thereon and absorbs the remaining two-thirds of the incident light, and thus, the light utilization efficiency of an RGB color filter is only about 33%. Therefore, in the case of a color display apparatus or a color image sensor, most of the light loss occurs in the color filter.
Meanwhile, as the number of pixels of a color image sensor has increased, the size of the pixels has decreased. Therefore, the amount of a light reaching each pixel has decreased, and thus, a method of improving the light utilization efficiency of an image sensor has become very important.
Recently, to improve the light utilization efficiency of a color display apparatus or a color image sensor, use of a color separation device, together with a color filter has been attempted. A color separation device separates incident light into different colors according to the diffraction and/or refraction properties of the device which vary according to wavelength. Light, thus separated into colors, is then transmitted to corresponding pixels. Thus, light of a non-corresponding color is refracted and/or diffracted away from the respective color filter of a pixel of a and is, instead, transmitted to an adjacent pixel of a corresponding color. Thus, the overall efficiency of a color display apparatus or color image sensor including the color separation device may be improved.
However, when light separated by a color separation device is incident on a color filter, some of the incident light may not be vertically incident on the color filter and, rather, may be incident on the color filter at a tilted angle, according to wavelength. Due to such a tilted angle of incidence, when the light is transmitted through the color filter and reaches a sensor array, the light may be incident on a sensor array corresponding to an adjacent pixel, rather than on a sensor array corresponding to the proper pixel. Thus, the light utilization efficiency of a color display apparatus or color image sensor including the color separation device is decreased and cross-talk between adjacent pixels is increased.